1. Field of the Invention
This invention relates to a thermosetting resin composition having a very low metal-corrosiveness, an excellent strength, an excellent impact resistance and a small molding shrinkage.
2. Description of Prior Art
In recent years, thermosetting resins have been used in a remarkably increased amount in the field of coating material for electronic parts because of their excellency in adhesion, insulation, moisture resistance and heat resistance. However, thermosetting resins are brittle, although they are high-strength materials. Also, when used as a coating material for electronic parts, they shrink during setting, and hence, stress is applied to the semiconductor elements coated by them. If the stress is large, the elements becomes fractured in some cases.
In order to solve the above problem, it has been tried to use a thermosetting resin composition obtained by blending a thermosetting resin with a rubber or a modified rubber or a rubber-modified thermosetting resin obtained by preliminarily reacting a thermosetting resin with a rubber.
However, when a thermosetting resin composition obtained by blending a thermosetting resin with a conventional rubber material is used for coating a semiconductor, metal ions and other impurities resulting from the emulsifier contained in the rubber material and from the use of a coagulant cause corrosion of lead wires (aluminum wires in many cases) of the semiconductor.